Moot : For a normal Tamiya type 540 2xvent Johnson motor, I used from 47-51mm rollout ... depending on track. Using 60T(48P) spur & from 36T-40T(48P) on Jaco Nitro Shoes foams. Further 60wt-front&50wt-rear oil with AE red-front&AE gold-rear springs. Remember that especially with stock your drive-train has to be 200% effiecient as every little part has an influence. If you are looking at hop-ups, definitely consider the Square TI input shafts; carbon drive shaft; ceramic bearings (I like ACER). Use a piece of car shammy with the vent holes cut open and keep it wet before going on the track(I use a mediacal syringe with water). This is cheap, ligther than a heatsink and even try Nitro Freeze spray to keep it really cool. Also change you pivot blocks from the stock set to 0deg-front & 1deg-rear.
Hope it helps!
Vance